“My husband is willing to terminate his parental rights to our daughter, I want to do this before filling for divorce in Washington State. Can we do this? And how?”
No, you cannot do it. And even if you could, it’s very ill-advised. No matter what you think of him, your daughter will always know that she is half you, and half her father.
Think of how your daughter would feel to think that one parent so didn’t want her that they were willing stop being her parent – and that the other parent thought so little of fully one-half of who she (your daughter) is, that they allowed it?
How selfish can you be?